Mobile processing-systems, such as portable computers and personal digital assistants, are often provided with the ability to establish wireless connections with other processing systems. Such wireless connections enable a user to access internet sites while traveling. A user thus equipped is able to obtain real-time information from an internet site and to act immediately on the basis of that information. For example, a user on the way to the airport may use a mobile processing-system to discover that a flight has been cancelled and that it may be preferable to simply turn around and go home.
As a practical matter, however, it is difficult for a user of a mobile processing-system to conveniently acquire timely information while traveling. The process of identifying and accessing a web site can be cumbersome and difficult to attend to while coping with the exigencies of travel. In addition, the speed of wireless data transmission is itself limited by numerous physical constraints. For example, high-speed data transmission requires high bandwidth. Such bandwidth may not be available simply because a finite spectrum must be shared by many channels. Inadequate signal-to-noise ratio, resulting from noise or multi-path reflections, can result in high error rates, which in turn require frequent retransmission of data packets.